1. Field of the Invention
This invention relates to an antenna for use with a wireless communications device and more particularly to a fast and efficient method of manufacturing low cost antennas for cellular telephones and other wireless communications devices. This is accomplished by reducing the number of components in the antenna assembly and developing manufacturing techniques that are reliable, repeatable and consistent.
2. Description of the Art
The wireless communications industry is growing at an alarming rate. The growth is, for the most part, driven by the cellular telephone industry. The fact that cellular telephone usage is becoming very affordable allows almost everyone to use them. Along with this astonishing growth comes stiffer competition at every segment of the business. Any provider of products or services to the industry is forced to search for new ways to reduce the cost of the products they supply. Handset manufacturers especially realize they must reduce costs on every component of the handset to stay competitive in the market.
Currently, there are several types of antennas that are used for wireless devices. Antennas for cellular handsets may be categorized into two main groups, that is, the fixed stubby antenna and the retractable antenna. The prior art stubby antenna illustrated in FIG. 1 is usually a 1/4 wave-length antenna and is simply a helical-shaped conductor (spring) attached to a metal connector with a cover enclosing the same. The conventional method of construction is to machine or die-cast a connector from metal, attach a helical-shaped radiator thereto by soldering or crimping and then attaching a cover to protect the antenna. The helical-shaped radiator is simply a wire that is wound into a spring by using conventional spring winding techniques.
The prior art retractable antenna of FIG. 2 is a modified stubby antenna with a conductive elongated radiator that slides through the center of the stubby antenna. The conductive whip section may be retracted into the phone while not in use or extended for enhanced performance. Inherent design features of the retractable antenna limit performance and manufacturing efficiency. One problem that occurs in the prior art antennas is the fabrication of the helical-shaped radiator (spring). If the desired spring geometry involves anything other than the normal spring design, it is difficult, if not impossible to produce. This is due to the normal process limitations of the spring winding technology. Also, depending upon the initial setup of the spring winding machine, variations in coil dimensions are common. Further, depending upon the material used, unwanted stresses are induced into the spring material while it is being formed. Unless the springs are post-treated to remove the stresses, the spring dimensions can change over time, causing electrical performance variations. Still another issue involved with the conventional design is the reliability of the connection of the spring to the connector.
An antenna is described for use with a wireless communications device such as a cellular telephone or the like wherein the antenna includes a helical radiator having a connector at one end thereof which is electrically connected thereto. The radiator and the connector are of one-piece unitary construction which may be either an injection molded plastic material or a metal die-casting material. The radiator and conductor are metalized with an electrically conductive material. In a second embodiment of the invention, an elongated radiator is slidably movably positioned within the helical radiator. In yet another embodiment of the invention, an elongated radiator is positioned within the helical radiator with the helical radiator, elongated radiator and connector being formed of one-piece, unitary construction.
It is a principal object of the invention to provide a method for manufacturing an antenna which reduces part count, increases reliability, increases consistency and reduces cost of the antenna.
Still another object of the invention is to provide antenna designs which use metalized injection molded plastic or metal die-casting.
Yet another object of the invention is to provide an antenna which is fabricated by means of a single shot plastic injected molded process or a metal die-casted process which is then metalized with a conductive coating and enclosed by a cover.
These and other objects will be apparent to those skilled in the art.